找竅門(mén),怎樣算簡(jiǎn)便就怎樣算.
(1)
5
6
×
6
5
-
9
10
÷
9
5

(2)4-
5
11
-
7
11

(3)3 
1
5
×[(1
2
3
+
1
5
)×2
1
7
]
(4)[
3
4
-0÷( 
1
7
+
2
13
 )]×1
1
3

(5)20 
1
100
×83+1.7×200
1
10

(6)
4
5
÷[(
5
8
-
1
2
)÷
5
8
].
分析:算式(1)(4)可根據(jù)四則混合運(yùn)算的運(yùn)算順序計(jì)算即可,即先算乘除,再算加減,有括號(hào)的要先算括號(hào)里面的.、
算式(2)可根據(jù)一個(gè)減兩個(gè)數(shù),等于減去這兩個(gè)數(shù)的和的減法性質(zhì)進(jìn)行計(jì)算;
算式(3)(6)可將中括號(hào)中的算式根據(jù)乘法分配律進(jìn)行計(jì)算.
算式(5)可先根據(jù)乘法算式的性質(zhì)將20.01×83變?yōu)?00.1×8.3后,再根據(jù)乘法分配律進(jìn)行計(jì)算.
解答:解:(1)
5
6
×
6
5
-
9
10
÷
9
5

=1-
9
10
×
5
9
,
=1-
1
2
,
=
1
2


(2)4-
5
11
-
7
11

=4-(
5
11
+
7
11
),
=4-1,
=3;

(3)3
1
5
×[(1
2
3
+
1
5
)×2
1
7
]
=
16
5
×[(
5
3
+
1
5
)×
15
7
],
=
16
5
×[
5
3
×
15
7
+
1
5
×
15
7
],
=
16
5
×[
25
7
+
3
7
],
=
16
5
×4,
=12
4
5
;

(4)[
3
4
-0÷( 
1
7
+
2
13
 )]×1
1
3

=[
3
4
-0
4
3
,
=
3
4
×
4
3

=1;

(5)20
1
100
×83+1.7×200
1
10

=20.01×83+1.7×200.1
=200.1×8.3+1.7×200.1,
=(8.3+1.7)×200.1,
=10×200.1,
=2001;

(6)
4
5
÷[(
5
8
-
1
2
)÷
5
8
]
=
4
5
÷[(
5
8
-
1
2
)×
8
5
],
=
4
5
÷[
5
8
×
8
5
-
1
2
×
8
5
],
=
4
5
÷[1-
4
5
],
=
4
5
÷
1
5
,
=4.
點(diǎn)評(píng):完成有關(guān)于分?jǐn)?shù)的四則混合運(yùn)算時(shí)要細(xì)心,注意通分約分.
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